Download d-GMM

The d-GMM(DETECT) is a digital ground movement monitoring instrument based on
YieldPoint‟s d-Tech technology. The sensor consists of two separate components the electronic
probe and the aluminum target between which there is no physical connection. Thus we refer to
the sensor as being „non-contact‟ in operation, and because the electronic probe unit can be
hermetically sealed, it will function indefinitely underwater and, with no moving parts is virtually
immune to blast vibration.
On-board the d-GMM (DETECT) the following digital operations are conducted;
1. The inductance variations of the sensor associated with relative motion of the aluminum
target are determined.
2. the temperature is determined by a digital temperature sensor.
3. A micro-controller used the inductance value, the temperature and a series of calibration
coefficients to calculate the displacement in directly in mm.
4. An RS485 transceiver transmits a serial (9600,8,N,1) ASCII data-stream from which
includes: a unique Sensor_ID, the Sensor_Type, the Temperature and Displacement data.
5. These signals can be carried over long lead wire lengths, and can be read using the
Manual Interrogation Unit, d-LOGGER Data-loggers or a DESTINY monitoring system.
Advanatges of the digital design include:
1. Information can be sent over long lead-wire lengths - orders of magnitude further than analog
voltage signals.
2. Using a serial signal many channels of information can be sent along a single pair of wires,
which reduces price and minimizes the time required for any repair.
3. If accidentally severed, lead-wires can be twisted together as a temporary fix.
4. Expensive A/D conversion has already been performed in the sensor so that Data Acquisition
can be built around low cost micro-controller.
5. Output in real world units decreases the cost of data interpretation and increases the number
of personnel who can use the data. Many times data gets trapped in an engineer‟s spreadsheet
program.
For Installation the following items are required:
1. d-GMM(DETECT) + Manual Interrogation Unit (d-READER)
2. Ratchet socket driver with 13/16” socket
3. 2 rolls of electrical tape.
4. Expansive foam or rock bolt epoxy
5. Drain tube for wet holes.
d-GMM(DETECT) User Manual Jan 2011
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